I would suggest Hercules and Juggs. Hercules will carry you all the way to the GM and you can use him for that fight to. Juggs will do wonders against the GM. His unstoppable charges gives you room to recover if you make a mistake and he is immune to reverse controls.
I don't remember much about the chapters before, but the Grandmaster himself can be done with basically anyone, especially if you study the fight carefully. You might wanna bring someone with DOT effects though, since one of his challenges is to inflict a damaging effect onto him.
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